1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, and more specifically, to a developer to develop an electrostatic latent image of a photoconductive medium with a toner.
2. Description of the Related Art
Conventionally, a developer for an image forming apparatus transfers toner from a developing casing to a developing roller using a toner supplying roller. The developing roller rotates and transfers the toner attached to an outer circumference thereof to a photoconductive medium so as to develop an electrostatic latent image of the photoconductive medium. Recently, as the life span and the toner capacity of developers increases, the size of toner chambers is also increasing. The toner chambers are conventionally made of a plurality of small cylinders rather than a large single cylinder in consideration of its appearance and mountability in image forming apparatuses.
FIG. 1 shows an example of a developer having a toner chamber which is formed with a plurality of the small cylinders as described above. Referring to FIG. 1, the developing casing 10 is provided with a first toner chamber 11 and a second toner chamber 12, each having a circular bottom side. The first and the second toner chambers 11 and 12 are filled with toner 13.
Further, the first and the second toner chambers 11 and 12 of the developing casing 10 are provided with agitators 20 and 20′, respectively, for agitating the toner 13. The first agitator 20 (the second agitator 20′ has the same structure as the first agitator 20, and therefore, only the first agitator 20 is described) includes a rotating member 21 and a resilient wing 22 attached to one end of the rotating member 21. As the resilient wing 22 rotates, one end makes contact with the wall of the first toner chamber 11 thereby agitating and transferring the toner 13.
A toner supplying roller 30 is rotatably disposed in the first toner chamber 11 of the developing casing 10. A developing roller 40 is rotatably disposed at the developing casing 10 so that the toner 13 can be supplied from the toner supplying roller 30. A regulating blade 50 to uniformly regulate the toner layered on the developing roller 40 is provided near the developing roller 40.
According to the above developer, during a printing operation, each agitator 20 and 20′ rotates and agitates the toner 13 in the first and the second toner chambers 11 and 12 respectively, while also transferring the toner from the second toner chamber 12 to the first toner chamber 11. The toner is transferred to the developing roller 40 by the toner supplying roller 30 in the first toner chamber 11. Finally, the toner is transferred to a photoconductive medium (not shown) by the developing roller 40 so as to develop the electrostatic latent image of the photoconductive medium.
However, conventional developers for image forming apparatuses as aforementioned have a shortcoming in that the toner 13 is apt to accumulate in the first toner chamber 11, which usually does not have a enough space. The agitators 20 and 20′ disposed in the first and the second toner chambers 11 and 12 of the developing casing 10 rotate and push the toner toward the first toner chamber 11 that is adjacent to the developing roller 30. Accordingly, the pressure of the toner in the first toner chamber 11 is increased and toner may be leaked out through both ends of the developing roller 30. In addition, the toner stress increases so that the image quality rapidly deteriorates.